Furnace plant for consuming raw coal dust



Aug. 16, 1949. E. A. LEMAxRE FURNACE PLANT FOR CONSUMING RAW COAL DUST 2Sheets-Sheet l Filed Sept. l, 1945 Fig. 5.

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Aug. 16, 1949. E. A. LEMAIRE l FURNACE PLANT FOR CONSUMING RAW COAL DUST2 Sheets-Sheet 2 Filed Sept. l, 4 1945 sczenm I AQCH El N 1 CHAR! GRATE,

Patented ug. 16, 1949 UNITED STATES PATENT orpi-cg FURNAGE rLAN'rFon.consnmdaaw f COAL DUST Edouard.. Auguste Lemaire, Grencblegrrance, as-

signor to Socit; Anonymev La Mure-Co'm' bustibl'es et- Industrie, a'corpora-tion of' France Application September 1, 1945,. Serial: No.`614,011Y

p In France April 6, 1941` Section 1", ,Pill'rli'cl Law 690, August 8,1946 Patent` expires September 6; 1961' (c1. rut- 28)l 4 Claims. 1 It isknown that heretofore fuels has been carried out practically byresorting to either of the two following methods, namely, an oldermethod wherein more .or less small fuel grains are burnt on hand;operated grates or automatic gra-tes or in furnaces of different types,and a more recent method wherein use is made of' the spontaneousself-ignition of coal crushed into very thin dust or powder. Thelast-named heating method made lit possible to gain advantagev of. coallines or smells which are produced in huge quantities in. allcollieries, provided of course that the hardships andcosts whichaccompany the crushing and: pulyeri'zing operations arel taken intoaccount. l

It is an object of the present inventionto permit direct use ina specialfurnace plant ofv coal fines yor smalls of a caliber or gage. equal to.2. and. .3 millimeter without requiring' any'I crushing or pulverizingoperation, such. nes being used as they are produced in the colliei-iesin proportion. as coals are being prepared.

Another object of theinvention is tot provide an improved heating plantwherein there is produced by means of an auxiliary furnace in ahoppershaped combustion chamber an ascendlngcolumn of hot gases whichAis guided up along- .one facev of said chamber and brought back, afterstriking. an upper deflector, along its opposite `face, soW that thereis generated in the combustion chamber and due to the turbulence which:prevails therein a driving effect and an automatic classifying of thecoal iines, the. latter being transferred depending upontheir volume.into thoserthermal4 zones f the chamber which are most favorable. to en-2 chamber until their carbon content'is exhaustedl by the combustionAmedium at high temperature a d at a relatively high speed' and understrong turbulence. y e

With these and such other objects in view as will incidentally appearhereafter, the invention` comprises the novel construction andarrangement of parts that will'now be described in detail with referenceto the 'accompanying diagrammatic drawings exemplifyi-ng the same andforming a part of the present disclosure.. u

heating. by sona the drawings- Figure' 1T isa view illustrating byarrows the probable path of the hot gasesthrough the combustion chamberci` afurnace plant built according tothe invention.

Figln'e 2 is a vertical sectional view showing a constructional form ofsuch furnace plant as applied to" the heating of an overhead steamgenerator including a tubular nest and header.V

Figure 3 is a transverse sectional view on. the irregular line A-AofFig. 2.

In. accordance with. the showing .of Figs. 2 and 3,. the heating plantaccording to the invention comprises a pilot furnace I the function ofwhich isi essential although its output only represents a small fractionof the contents of the receiver. The: pilot furnace I is arranged at thelower end of; the combustion chamber having its sections or compartmentsdesignated'by 2, 3, 4 and 5 and provided adjacent its lower end with anignition arch 6 over the'` pilot furnace I.

Advantageously and by way of examplev the pilot furnace l is constitutedby an automatic chain grate la`A of known type, said automaticgratebeing chiefly constituted by an endlessV chain to which. atranslationalmovemerit is imparted inthe direction extending from adistributing hopper 'l to a tight ash pit 8 the lower opening lof. whichisv controllable by means of a sliding damper 8a, said pit beingdischargeable `for example into one of a plurality of trucks such asy8b.

The chamber compartment 2 of smaller sectional area and the chambercompartment 5 of larger sectional area of the combustion chamber 'haverectangular sectionalV areas and are interare` substantially verticalexcept its rear wall I2 l whose inclination is between 20 and 40 to theVvertical'depending uponl the arrangement .of the heat receiver I l.

An' inwardly projecting screeny like arch I3 partly intercepts the upperchamber section 5. This arch I3 stops or deflects the vertical risingcolumn of gas and thus protects the iorwardgpart of the tubular pile ofthe heat receiverv II against `the direct action of this gas.

A first adjustable secondary air inlet I4 is provided in thecombustionchamber adjacent its faceawhiclrforms the extension of theinclined VA fan I'I provided with a nozzle I'I blows the major portionof the primary combustion air through the pilot furnace I.

The plant also comprises a feeding hopper I8 containing a reserve .ofignition coal and provided with a valve I8. It also comprises a seriesof raw coal fine feeding hoppers I9, 26 supplying an injection feedingworm Y2l actuated by a pulley 2|a on which passes a driving belt orchain 2lb. Y

A particular feature of the plant is tozbe found in the fact that mostof the non-burnt portions which may be driven through the heat receiverII are taken back by hoppers 22, 23 and are reintroduced into thecircuit through tubes 24, 25 which are imbedded in the reserve of coalfines.

The operation takes place as follows:

After ring up the pilot grate Ia, its continuous translational movementintroduces into the furnace a layer of ignition coal of adjustablethickness and speed. This coal gets hotter under the action of a partialcombustion under the ignition arch 6 and reaches a position just' underthe chamber 2. This coal then undergoes brisk combustion and stronglypreheats the total quantity of air injected by the fan I'I (through thenozzle Il) and also the walls of the sections 2 and 3 of the'combustionchamber.

Gases and flames guided up through the chamber 2 constitute a high speedascending current whichfollows up the vertical wall 26 and is moved olfat a position corresponding with the opposite position whence theinclined wall I2 rises vertically, thereby creating, after the gaseous-streams have been deflected by the deviating arch I3, a partialdescending return of such gases along the inclined wall I2 (Fig. 1).This action is very useful and is automatically amplified by the liftingstrengthV of the gaseous vein due to its average Vtemperature beingstrongly raised by comparison with the ambient Raw coal fines areintroduced in sheet form at I by the worm conveyor 2| into the fluidcurrent as it eiects its return or downward path. Such fines glide downalong the wall I2 until they come into contact with the rising fluidcurrent, whereby in the impact region an actual pneumatic sorting actiontakes place. The ne particles of coal forming a coal dust cloud are castolf and ignited in the chambers 4 and 5. Coal particles of average sizeburn in cloudy suspension in the chamber 3, While the bigger coalparticles fall upon the pilot grate Ia and immediately undergo. livelycombustion under the action of the powerful heating effect as caused bythe end of the combustion of the ignition coal.A

Actually there is not, as above stated, any static suspension ofgrainand dust in a chamber through which the speed of the fluid currentprogressively dwindles down. The action is rather atmosphere adjacentthe wall 2,479,376 v ly. .Y

a rapid revolution of the ignited coal particles as they are taken andcast off several times at different levels until their carbon content isexhausted Yby the combustion-fostering medium, at a high temperature,and at a relatively high speed and shown) and by the regulatable draftthrough the chimney 28 whose sectional area and draft power `arecontrollable by means of a sliding damper 23a. Its purpose is to preventthe formation of any gaseous unburnt portion. This additional air ismixed with the ascending air current, as soon as it is created, and isafterwards heated and partake's of thef'pneumatic draft.

Advantageously a further secondary air inlet I Varranged horizontally isprovided underneath the screen-like arch I3 for the purpose of assistingin the deflection of the rising streams and of ensuring in the chambercompartment 5 a quicker combustion of fine glowing coal dust.

The shoulders I0 which surround the combustion chamber on three facesthereof are adapted `to build up reserves or heaps of hot coal which areconstantly renewed as the coal slope tumbles down under its own weight.Such reserves increase the available heat provision during variations inoperating conditionsof the furnace. Additional shoulders `such'asl 9 maybe also provided on the oblique walls when coalfines or smalls ascommonly dealt with arev liable to furnish many ashes and are hard toignite. Y

However, in the case of long burning coal fines, the controls of thepilot grate Ia make it possible `to strongly reduce and'even to do awaywith the introduction of igniting coal as soon as the combustion chamberhas been suiciently pre-heated and creates suchv a radiation as willenable the combustible dust to be spontaneously ignited.

Whatever cllnkeris left by the combustion of coal particles is resolvedin the combustion chamber into nuts which partakeof the movement of coaliinesand fall upon the grate I a inlvertical alignment with the reararchV 21 (Fig. 2) las soon as they have a sufficient size toovercome bygravitational power the lifting strength Vof the gaseous flux in thechamber compartment 2. Such nuts are then coalesced to the layer ofvcoal clinker which were burned on thefurnace grate Ia. All residualmatters are continuously dumped into the tight ash pit 8 owingto thetranslational movement of the grate la.v As most of the combustion airflows through th pilot grate Ia, the portion of fuel which is stationaryupon the apronshaped portion of this grate is burntin'a large excessrofair. This constitutes a very valuable advantage vsince it assists in theproduction of clinker devoid of unburnt solid matters.

Minor constructional details particularly as regards the heatreceivervrhlght beyaried to suit practical requirements withoutdeparting from the scope of the subjoined claims.

What is claimed is:` Y

1. A furnace plant for burning raw coal fines, comprising a pilot grateof movable catenary endless structure, means including .a fan and nozzlefor feeding primary combustion airalong said grate, means including'ahopperand valve for feeding divided coal upon the upper Vrun of saidgrate, an ignition `arch over'said grate, means forming'ra `combustionchamber extending upwardly over the grate beyond said arch, said chamberbeing dened nearest to said arch by aivertical wall and on the voppositeside by an oblique wall upwardly diverging from Vsaid vertical wall,said oblique kwall havingl spaced shoulders projecting into said,chamberja deilector inwardly projecting into said chamber from ;.its

vertical wall, r'egulatableV means for feedingcoal said grate, meansforming a combustion chamber ya extending upwardly over the grate beyondsaid arch, said chamber being defined nearest to said arch by a verticalwall and on the opposite side in the direction of the lgrate motion byan oblique lwall upwardly diverging from said vertical wall,

said oblique wall having spaced shoulders projecting into said chamber,said chamber being divided into several superimposed sections, ahorizontal arch deflector inwardly projecting into said chamber from theupper region of said vertical wall, worm feeding means for bringing aregulated quantity of coal dust through said oblique wall for it toglide down therealong in sheet form towards said grate, a heat receiversurmounting the upper section of the chamber, and secondary air inletmeans including an air inlet in the upper part of the chamber adjacentthe heat receiver and another air inlet through the vertical chamberwall just under the arch deector.

3. A furnace plant for burning raW coal fines. comprising a pilot grateof movable catenary endless structure, means including a fan and nozzlefor feeding primary air along said grate, means including a hopper andvalve for feeding divided coal upon the grate, an ignition arch oversaid grate, means forming a combustion chamber extending upwardly overthe grate beyond said arch, said chamber being defined by a verticalwall and by an opposite wall extending obliquely over the major portionof its length so that the sectional area of the chamber increasesupwardly, said oblique Wall having spaced shoulders projecting into saidchamber for retaining hot coal heaps, said chamber forming foursuperimposed sections, a horizontal arch del flector inwardly projectingfrom the upper region of the vertical wall, adjustable feeding means forbringing coal dust through said oblique wall for it to glide downtherealong towards the grate, a heat receiver surmounting the uppersection of the chamber, a chimney communicating with said upper section,duct means leading from said upper section for bringing unburnt coaldust back to said adjustable feeding means, and secondary air inletmeans including an air inlet in the upper part of the chamber andanother air inlet through the vertical chamber wall just under the archdeector.

4. A furnace plant for burning raw coal fines, comprising a pilot gratecapable of effecting a translational motion, means for bringing dividedcoal and primary air to said grate, an ignition arch over said grate,means forming a combustion chamber extending upwardly over the gratebeyond said arch, said chamber being defined by a vertical wall on oneside and by an oblique wall on the opposite side so as to flareupwardly, said oblique wall having spaced shoulders for retaining hotcoal heaps, an arch deilector projecting from the upper region of saidvertical wall, adjustable feeding means for bringing coal dust throughsaid oblique wall for it to glide down in sheet form therealong towardssaid grate, a heat receiver over the top of said chamber, a chimneycommunicating with the chamber top, damper means for regulating thedraft through the chimney, hopper and duct means leading from thechamber top for bringing down unburnt coal dust back to said adjustablefeeding means, and secondary air inlet means including an air inlet inthe upper part of the chamber and another air inlet through the verticalwalljust under the arch deflector.

EDOUARD AUGUSTE LEMAIRE.

REFERENCES CITED The following references are of record in the file ofthis patent:

UNITED STATES PATENTS Number Name Date 1,450,154 Kupa Mar. 27, 19231,452,045 Hawley Apr. 17, 1923 1,630,387 Jacobus May 31, 1927 1,661,408Chapman Mar. 6, 1928 1,714,678 Kreisinger May 28, 1929 1,719,874 ChapmanJuly 9, 1929 1,790,750 Jacobus Feb. 3, 1931 1,849,095 Keenan, Jr Mar.15, 1932 q 1,898,479 Coghlan et al Feb. 21, 1933 1,918,401 Kleinow July18, 1933 1,942,687 Daniels Jan. 9, 1934 1,947,460 Coutant Feb. 20, 19341,970,109 Stratton Aug. 14, 1934 2,072,450 Hobson, Jr Mar. 2, 19372,110,452 Moyer Mar. 8, 1938 2,386,336 Mosshart Oct. 9, 1945 FOREIGNPATENTS Number Country Date France Jan. 22, 1923

